Amazon Web Services, broken out initially in the first quarter of 2015, should be a $12.5 billion business this year, Doshi told CNBC's "Squawk Box," calling AWS the "800-pound gorilla" in the cloud.

"There's definitely concern around Google [part of Alphabet] and Microsoft ... coming in and undercutting Amazon," he said. "But from a technical standpoint, we think Amazon is on par with Microsoft and definitely far ahead of Google."

Amazon is also making inroads on Google's bread and butter, Doshi said. "I think Amazon is also starting to take away search from Google's search on the retail side."

After the closing bell Thursday afternoon, Amazon is expected to report earnings of 58 cents for the first quarter on nearly $28 billion in revenue, according to the consensus estimate from Thomson Reuters.

In the year-ago period, Amazon had a loss of 12 cents per share on revenue of $22.72 billion. But after that, the e-commerce giant posted three straight quarters of earnings, finishing up 2015 with a $1 per share profit in the fourth quarter on $35.75 billion in revenue.

Matthew Staver | Bloomberg | Getty Images

Jeff Bezos, chief executive officer of Amazon.com

"The core business will continue to do well. They added about 3 million Prime members towards the end of last year. I think that should flush through to this quarter. So that could provide upside into the North America business," Doshi said.

Meanwhile, he downplayed concerns surrounding a possible "deep investment cycle" and squeezed operating margins. "They've gone through a multiyear investment cycle. Now they're really starting to come out of that." Though he does project some investment.

"We're expecting modest margin compression in the first and second quarter, with margins expanding in the back half of the year," Doshi predicted, pointing out margins did "expand on a year-over-year basis for the past five quarters, after many quarters of margins being compressed."

— Disclosure: Mizuho has performed investment banking services for Amazon. The firm also makes a market in Amazon and provided non-securities-related services to Amazon in the past 12 months.

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